Narrative:

At approximately XA30; we began losing all data link connections with aircraft over the pacific ocean. Losing data link constitutes the loss of ads and cpdlc. We effectively lost communications with 50+ airplanes that were connected on data link and under ZOA control. Once it was determined that we were no longer connected to these planes; the controllers had to attempt to reestablish separation on the pairs that were separated using distance based longitudinal and also attempt to reestablish communications with these aircraft. After several ecs (external communications sever) and channel swaps; the problem remained. At approximately XC00; ads and cpdlc began working again. No explanation was given for the cause of the outage or what fixed it. The next day; at approximately XA00 we again lost data link communications on all of the fans equipped airplanes over the pacific. The same attempts were made to correct the problem that were made the day before; but to no avail. Sita was called and replied that they were not having any problems. Around XC30; service began to be restored. Later ZOA received a facsimile from sita stating that there was an unplanned outage for 2 1/2 hours which coincided with the loss of data link. Apparently; these 2 instances likely had different causes. This has been an ongoing issue at ZOA since 2005 when OCEAN21 was turned on. There have been several ucr's filed and some half-hearted attempts to fix the problem; but this continues to be a not only a safety issue; but a service issue as well.

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Original NASA ASRS Text

Title: ZOA CTLR DESCRIBED FAILURE OF OCEANIC DATA LINK; IE; ADS AND CPDLC ON 2 CONSECUTIVE DAYS; INDICATING THIS TYPE OF PROB IS ONGOING.

Narrative: AT APPROX XA30; WE BEGAN LOSING ALL DATA LINK CONNECTIONS WITH ACFT OVER THE PACIFIC OCEAN. LOSING DATA LINK CONSTITUTES THE LOSS OF ADS AND CPDLC. WE EFFECTIVELY LOST COMS WITH 50+ AIRPLANES THAT WERE CONNECTED ON DATA LINK AND UNDER ZOA CTL. ONCE IT WAS DETERMINED THAT WE WERE NO LONGER CONNECTED TO THESE PLANES; THE CTLRS HAD TO ATTEMPT TO REESTABLISH SEPARATION ON THE PAIRS THAT WERE SEPARATED USING DISTANCE BASED LONGITUDINAL AND ALSO ATTEMPT TO REESTABLISH COMS WITH THESE ACFT. AFTER SEVERAL ECS (EXTERNAL COMS SEVER) AND CHANNEL SWAPS; THE PROB REMAINED. AT APPROX XC00; ADS AND CPDLC BEGAN WORKING AGAIN. NO EXPLANATION WAS GIVEN FOR THE CAUSE OF THE OUTAGE OR WHAT FIXED IT. THE NEXT DAY; AT APPROX XA00 WE AGAIN LOST DATA LINK COMS ON ALL OF THE FANS EQUIPPED AIRPLANES OVER THE PACIFIC. THE SAME ATTEMPTS WERE MADE TO CORRECT THE PROB THAT WERE MADE THE DAY BEFORE; BUT TO NO AVAIL. SITA WAS CALLED AND REPLIED THAT THEY WERE NOT HAVING ANY PROBS. AROUND XC30; SVC BEGAN TO BE RESTORED. LATER ZOA RECEIVED A FAX FROM SITA STATING THAT THERE WAS AN UNPLANNED OUTAGE FOR 2 1/2 HRS WHICH COINCIDED WITH THE LOSS OF DATA LINK. APPARENTLY; THESE 2 INSTANCES LIKELY HAD DIFFERENT CAUSES. THIS HAS BEEN AN ONGOING ISSUE AT ZOA SINCE 2005 WHEN OCEAN21 WAS TURNED ON. THERE HAVE BEEN SEVERAL UCR'S FILED AND SOME HALF-HEARTED ATTEMPTS TO FIX THE PROB; BUT THIS CONTINUES TO BE A NOT ONLY A SAFETY ISSUE; BUT A SVC ISSUE AS WELL.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.